Electrical control system



Dec/:.28, 1948l w. G. WAMSLEY ELECTRICAL CONTROL SYSTEM Filed June 14,1946 Patented Dec. 28, 1948 UNITED STATES PATENT OFFICE ELECTRICALCONTROL SYSTEM Wmiam G;wams1ey, Detroit, Mich.

Application June 14, 1946, Serial No. 676,652

(Cl. S18-445).

1o claims 1 This invention relates generally to electrical controlsystems which are adapted, among other uses, for controlling multi-speedhoists, elevators and the like.

Primary objects of this invention are to provide a novel control systemfor a. raising and lowering mechanism; to provide a system forIcontrolling a raising and lowering mechanism which provides for one ormore automatically controlled steps of acceleration and deceleration; toprovide a system having control means operable during a predeterminedtravel portion of the mechanism to render the mechanism ineffective tooperate at high speed; to provide means whereby when the mechanismapproaches its limit of travel lts speed is automatically changed toslow speed before reaching the stop position; to provide such a systemutilizing energy storage apparatus, preferably condensers, whichco-operate in an improved manner with other elementsof the system tocontrol change in speed; and to provide a system which is simple toconstructandr operate. Other objects will be apparent ,from thespecification and the appended claims.

In the drawing, the sole figure shows a schematically arranged wiringdiagram for controlling a hoist.

Electrical energy from a suitable source of supply and of suitablevoltage is supplied by lines LI and L2 and is controlled by the usualline switches LSI and LSI. A manual pushbuttoncontrol station generallydesignated MS `is suitably positioned so that the operatory of thehoist, by pressing either the up button UB or the down button DB orreleasing both buttons, causes the hoist to move upwardly or downwardly.Initial inward movement of the button UB closes contacts UPZ foroperating the hoist in an `up ydirection at slow speed. Continued inwardmovement of the button UB opens contacts UPI, which causes the hoist tooperate in anup direction at high speed. Similarly the button DB acts toclose contacts DNZ and open contacts DNI to cauce the hoist to operatein a down direction at slow `and then high speeds respectively. Releaseof both buttons UB and DB causes `the hoist to stop. Even though theholst operator may immediately push either of the buttons UB and DB intohigh speed operation, such manual control of switch MS will not act toimmediately complete high speed operating connection for the hoistmotor, such completion being delayed `for a predetermined'time intervalby an accelerating control circuit I.

Manual switch MS comprises contacts UPI and UP2 which are closebybridging bars 'Ii und I8 respectively and which bars are electricallyconnected together as by a conductor I9. rihe bars I6 and I8 areapertured and are loosely carried on a push rod 20 extending through theapertures. A spring 2I is positioned around the rod 20 intermediate thebars I6 and I8 and acts to urge the bars I6 and I8 in a partingdirection. The rod 20 has spaced pins 22 and 23 therealong which limitmovement of the bars I6 and I8 by the spring 2| and are so spaced thatwhen the button UB and rod 2i] are held in the position shown, as byspring 24, the bar I8 will be in engagement with pin 23 and held therebyout of engagement with contacts UPZ. When the bar I6 is held incircuit-making position against the contacts UPI, the pin 22 is spacedoutwardly from the bar I6 so that upon inward movement of the button UB,pin 23 will have permitted the bar I8 to engage the contacts UP2 forcompleting an electric circuit therebetween prior to the engagement ofpin 22 with bar I6 so that at a partially inward Sosition of button UP,both sets of contacts UPI vand UP2 will be in circuit-making position.Further inward movement of the button UB will cause pin 22 to engage barI6 and open contacts UPI. Similarly the down button DB has a rod 25, aspring 26 urging button UB outwardly, a spring 21 urging bridging bars28 and 29 connected by a conductor 30 in a parting direction, and pins3| and 32, so that upon inward movement of the vbutton DB, .bar 29closes the circuit between contacts DNZ, and subsequently bar 28 opensthe circuit between contacts DNI.

The cir-cuitA I includes an accelerating relay having oneterminal of itscoil AR directly connected to the line LI and its other terminalconnected through the contacts UPI and DN I to the line L2. A timingcondenser AC controls the interval between the initiation of actual highspeed operation and the time the operator sets the button UB or DB forsuch operation. This condenser AC is connected across the terminals ofthe relay coil AR and is normally maintained fully charged by normallyclosed circuit I. Upon deenergization of the accelerating relay circuitI due to manual movement of buttons UB or DB to high speed position, thecondenser AC discharges through and maintains the accelerating relaycoil AR energized for a predetermined time interval afterde-energization ofthe accelerating relay circuit I so that even ii thebuttons UB or DB are instantaneously moved from stop position tohigh-speed position, the low speed connection for the hoi-st `will beVmaintained for a predetermined time interval.

A low speed control circuit 2 is connected between the lines LI and L2and energizes the lowspeed relay having the coil LR. Starting from lineLI, this circuit 2 includes parallelly arranged, normally open contactsASI of the accelerating relay and normally closed contacts HSI of thehigh-speed relay, relay coil HR, and parallelly arranged branch circuitsconnected to the line L2. One of these branch circuits includes normallyopen contacts DSI of a decelerating relay having a coil DR. Another ofthe branch circuits includes normally open contacts US2 of an uprelayhaving a coil UR and contacts UP2 of switch MS. Another of the branchcircuits includes normally open contacts DNSZ of a downrelay having acoil DNR and contacts DN2 of switch MS.

A circuit 3 is arranged to actuate the up-relay coil UR so that uponenergization of the lowspeed relay coil LR or the high-speed relay coilHR, the motor I2 will operate in the direction to raise the hoist ateither slow or high speed. The circuit 3 starting from line LI includesthe normally closed contacts ULSI of the up-limit switch ULS, relay coilUR oi the up-relay, and normally open contacts UP2 directly conn-ectedto line L2. Circuit 3 also has a branch circuit extending from a pointintermediate coil UR and contacts UP2 which includes contacts US2 of theup-relay and holding contacts DSI of the decelerating relay.

A high-speed control circuit l controls the energization of the coil HRof the high-speed controlling relay and, when energized, operates themotor I2 at high speed in a direction depending upon whether theup-relay coil UR or the down-relay coil DR is energized. Circuit 4 extends from the line LI through normally closed contacts AS2 of theaccelerating relay, coil HR', selector switch contacts SSU, contactsULS2 of the up-limit switch ULS, contacts DNSI of the dcceleratingrelay, the holding contacts US2 of the up-relay, and contacts UP2 toline L2. A branch circuit extends from a point intermediate the coil HRand contacts SSU through contacts DLS2 oi the down-limit switch andthrough contacts SSD of the selector switch SS to a point intermediatethe contacts SSU and ULSZ, so that when the selector switch SS is in itsup position closing contacts SSU, it is immaterial, in so far asoperation in an up direction of the high-speed circuit 4 is concerned,whether the contacts DLS2 are open or are closed. When the selectorswitch SS is in its down position, opening the contacts SSU and closingcontacts SSD, the contacts DLS2 also control the energization of circuit4 so that when the hoist is adjacent its low limit and contacts DLS2 areheld open by the down-limit switch DLS, the hoist is rendered ineiectiveto operate at high speed until the hoist has moved upwardly enough toallow the contacts DLS2 to be closed by the down-limit switch DLS. Asecond branch circuit extends from the contacts DLS2 through normallyclosed contacts US! of the up-relay in parallel relation with contactsSSD, ULSZ, and DNSI.

A decelcrating control circuit 5 extends from line Li 'through thenormally open contacts HS2 oi the high-speed relay, the relay coil DR ofthe decelerating relay, and then branches into branch circuits to lineL2. One oi these branch circuits includes the contacts US2 of theup-relay and the contacts UP2 of the switch MS. Another of the branchcircuits includes the contacts DNS2 of the downrelay and the contactsDNZ of the switch MS. A third branch or holding circuit includes theholding contacts DSI oi the decelerating relay which are directlyconnected to line L2. A timing condenser DRC has its terminals connecteddirectly across the end terminals oi the relay coil DR and acts in amanner similar to the timing condenser AC to maintain the relay coil DRenergized for a predetermined time interval after the circuit 5 has beende-energiaed.

A down direction control circuit E extends from line LI through thenormally closed contacts DLSI `of the down limit switch DLS, the relaycoil DNR of the down relay, and contacts DN2 of switch MS to line L2.The circuit I also includes branch holding circuit through contacts DNS2oi` the down-relay and contacts DSI to line L2.

Energization of the relay coils UR or DNR closes contacts US3 and US4and DNS3 and DNS4 respectively ior rendering an electrical power circuit8 in condition to operate an electric motor I2 in a hoist-raising orhoist-lowering direction. Energization of the relay coils LR or HRcloses contacts LSI or HSS and HS4 respectively to cause the motor l2 tooperate at either a low or a high rate of speed. In the instance shown,circuit 8 is arranged to operate the direct current motor I2. Theparticular power circuit which is used is immaterial, as the motorcircuit per se does not form a part of this invention, and it will beobvious to one skilled in the art that an alternating current motor andpower circuit could be used. Motor I2 operates upon cnergization of oneof the relay coils UR or DNR and one of the relay coils LR or HR torotate the cable drum I4 to raise or lower the hoist (not shown).

Worm gears 33 and 34 are driven through suitable gearing 35 by the cabledrum I4. A downlimit switch actuating cam 36 is driven by the worm gear33 and an up limit switch actuating cam 3l is driven by the worm gear 34for actuating the down and up limit switch DLS and ULS respectively.Upon rotation of the cam 36, the down-limit switch DLS will rideupwardly on the cam nger 38 raising the down-limit switch push rod 39and opening the contacts DLS2. The contacts DLSI will remain closedbecause of the lost motion between the rod 39 and the loosely fittingbar 40 bridging the contacts DLSI. Bar 4i) therefore will not bedisengaged from contacts DLSI until the rod 39 has been moved by camfinger 38 further in an upward direction causing pin 4I carried by rod39 to engage and move the bar 4D out of circuit-making engagement.

The -lip-limit switch ULS is similarly constructed and its rod 42 issimilarly actuated by cam finger 43 to cause pin 45 to move bar 44 outof circuit making relation with the contacts ULSI subsequent to theopening of the circuit through contacts ULS2.

The operation of the control circuit is as follows: Closure of the lineswitches LSI and LS2 energizes the line conductors LI and L2respectively, which will immediately energize the accelerating relaycoil AR and its associated timing condenser AC due to the closedcondition of the contact members UPI and DNI. With the manual switch MSin the position shown, this is the only result of the closing of theline switches LSI and LS2. If now it is desired to cause the cable drumI4 to be rotated in a direction to raise the hoist, the up button UB ismanually pressed inwardly to close the normally open contacts UP2 whichcomplete the circuit 3 energizing the up relay coil UR. Energization ofthe coil UR opens the normally closed contacts USI and closes thenormally open contacts US2 to complete a circuit from the line LIthrough now closed contact members ASI, relay coil LR, and now closedcontact members US2 and UP2 to line L2. Energization of the relay coilLR closes the contact members LSI which, together with the closure ofthe contact members US3 and US4 which were closed by the energization ofthe up relay coil UR, causes the motor I2 to rotate the cable drum I4 atlow speed for up movement oi the hoist. It will be noted at this timethat the pin 22 of the up button UB has not as yet engaged the bridgingbar I6 of the up button UB to open the contact UPI and, therefore, aslong asthe up button UP is maintained in lthis position, the motor I2will continue to operate to raise the hoist at slow speed. If it is nowdesired to operate the hoist in an upward direction at a high speed, theup button UB is pressed inwardly further to cause the pin 22 to move thebridging bar I6 out of circuit-making position with the contacts UPI.This opening of the contacts UPI immediately de-energizes theaccelerating relay control circuit I. However, due to the chargedcondition of the timing condenser AC, the accelerating relay coil ARwill not immediately be dee-energized, but will act as the dischargecircuit for the timing relay condenser AC. Therefore, until thecondenser AC is substantially discharged, this coil AR will remainenergized holding the contacts ASI closed and the contacts AS2 open, andthe hoist continues to operate at the slow speed in an upward direction.Subsequent to the discharge of the timing condenser AC, the coil AR willbe de-energized, opening the contacts ASI and closing the contacts A82.Opening of the contacts ASI causes no change in the operation of themotor I2, since a parallel circuit around the contacts ASI through thenormally closed contacts. HSI is. maintained. Closure of the contactAS2, however, acts to energize; the relay` coil HR by closing thecircuit 4 which extends from the line LI through the contacts AS2, therelay coil HR, the now-closed contacts SSU., the now closed contactsULSZ, the closed contacts DNSI, the closed contacts US2, and closedcontacts UP2 to the line L2. Energization of the coil HR immediatelyopens the normally closed contacts HSI to de-energize the low-speedrelay coil LR. Energization of the high-speed relay coil HR also closesthe contacts HS3 and HS4 which, with the opening of the contacts LSI,due to deenergization of the low-speed relay coil LR, will place themotor I2 in a condition to rotate the cable drum I4 in a direction forraising the hoist at a high rate of speed, Energization of the coil HRalso closes contacts HSZ, completing the decelerating` control circuit5, contacts US2 and UP2 having been previously closed as hereinbeforedescribed, to energize coil DR and close contacts DSI, completing aholding circuit in to line L2 in parallel with contacts US2 and UP2.Energiz-ation of circuit 5 also causes the condenser DRC to becomecharged. Assuming that the operator wishes the hoist to be raised to itsuppermost position, yhe manually maintains the up button UB in thepresent innermost position with contacts UP2 closed and contacts UPIopen. As the cable drum I4 rotates it acts through the gearing 35 torotate the worm gear 34 until the up-limit switch actuating cam 3'Irotates so that the cam finger or lobe 45 thereoimoves the up limitswitch actuating rod 42` which Will rst open the contacts ULSZ, but dueto the lost-motion connection between the pin 43 and the bridgn -r ading` bar 44, the contacts ULSI will remain closed. Opening of thecontacts ULSZ de-energizes the aforementioned circuit 4, including thehighspeed relay coil HR, so that the contacts HS3 and HS4 will open andthe contacts HSI will close. Closure of the contacts HSI immediatelyenergizes the circuit 2 and the included low-speed relay coil LR throughclosed contacts US2 and UP2. The parallel branch circuit throughnow-closed contacts DSI will remain completed for a predetermined timeinterval subsequent to de-energization of circuit 5 because of thenow-charged condenser DRC which discharges through coil DR to maintainit energized for a predetermined time interval. If, as is the case here,the contacts UP2 are maintained closed, this discharge of condenser DRCis without eiect as far as continued low-speed operation is concerned.

Energization of the coil LR re-establishes a closed -circuit through thecontacts LSI and places the motor circuit in condition to operate themotor I2 and cable drum I4 at a low speed in an upward direction of thehoist, Continued upward movement of the hoist I4 will cause the up-limitswitch actuating cam lobe 45 to continue the upward movement of theup-limit switch bar 42 to take up the lost motion between the pin 43 andthe bridging bar 44' to open contacts ULSI to de-energize the circuit 3and the up-relay coil UR. De-energization of the coil UR opens thecontacts US2, US3, and US4 and closes the contacts USI. Opening of thecontacts US2 de-energizes the circuit 2 and the low-speed relay coil LR,opening the contacts LSI, the branch circuit through contacts DSI havingbeen previously de-energized as above described. The opening of thecontacts LSI, US3, and US4, as heretofore described, de-energizes thecircuit for the motor I2, and rot-ation of the cable drum will stop.

If now, instead of maintaining the up button UB depressed in the normalhigh-speed operation of the hoist, the operator had desired to reducethe speed of the hoist at an intermediate position, he would havereleased the pressure on the up button UB until the bridging bar I6moved upwardly to close the contacts UPI. Closure of the contacts UPIenergizes circuit I and the relay coil AR. Energization of coil AR actsto close the contacts ASI and open contacts AS2. Opening of lthecontacts ASZ de-energizes circuit 4 and the high-speed relay coil I toopen the contacts HS2, HSS, and HS4, and to close the contacts HSI.Closure of the contacts HSI energizcs the control circuit 2 and the coilLR of the low-speed relay, closing the contacts LSI to place the circuitfor themotor I2 in condition to operate the drum I4 in the. clockwise orup direction of the hoist at slow speed. If, after operating the hoistat low speed in an up direction as described, the operator desires tostop the same, he releases the up button UB, allowing the circuit 2through contacts UP2 to open to de-energize the lowspeed relay coil LRand to de-energize the circuit 3 of the relay coil UR whereby thecontacts US2 are opened. Contacts LSI, US3, and USII will be opened andthe circuit for the motor I2 deenergized to stop rotation of the cabledrum I4.

If, when the hoist was being operated in an upward direction at highspeed the operator immediately released all pressure on the up buttonUB, the contacts UP2 would be opened and the contacts UPI would beclosed. Closure of the contacts UPI energizes the circuit I and itsrelay coil AR to close the contacts ASI `of the lowspeed control circuit2 and to open the contacts AS2 of the high-speed control circuit 4. Aswill be presently explained, contacts DSI will remain closed for apredetermined timing interval to maintain relay UR energized.Consequently, closure of contacts ASI will energize the lowspeed controlcircuit 2 to energize coil LR for closure of contacts LSI to place thecircuit for the motor I2 in condition to operate motor I2 and drum I4 atlow speed in the up direction. Opening of the high-speed control circuit4 deenergizes the high-speed control relay winding HR which, ashereinbefore set forth, opens the contacts HS2, HS3, and HS4 and closescontacts HSI. Opening of contacts HS3 and HS4 de-energizes thehigh-speed portion of the circuit for motor I2. Closure of contacts HSIenergizes the by-pass or parallel circuit around the now closed contactsASI without effect. Opening of the contacts HS2 de-energizes thedecelerating control circuit 5, but the deceleration control relay willnot, however, immediately be de-energized because of the timingcondenser DRC which discharges through the relay coil DR and maintains,for a predetermined time interval, the contacts DS2 and DSI in closedcircuit position maintaining the branch circuits of low-speed and updirection control circuits 2 and 3 energized, even though, at the time,the up button UB was fully released, and the branch circuits thereof,through contacts UP2, were opened. After a predetermined time intervalthe condenser DRC will have discharged, and coil DR will berie-energized, so that the contact DSI will open to de-energize the lowspeed and up direction control circuits 2 and 3, including coils LR andUR. De-energization of coil LR causes the low-speed relay to open thecontacts LSI, and de-energization of coil UR causes the up relay to opencontacts US3 and US4. Opening of contacts LSI, USS, and US4 de-energizesthe control circuit for motor I2 and stops rotation of the cable drumI4.

When the hoist is being started in the upward direction from a point ator adjacent the low limit of its travel and the selector switch SS isarranged in the down position so that it closes the contacts SSD, thecircuit 4 of the high-speed relay coil HR is now caused to be controlledby the contacts DLS2 of the down-limit switch. As set forthhereinbefore, when the cable drum I4 is in a position in which the hoistis at or adjacent its low limit, the operating rod 39 will be held in araised position by the cam lobe 38 until the drum I4 has caused thehoist to be moved a predetermined distance from the bottom limit of itstravel. As was explained hereinbefore, this raised position of rod 39will maintain contacts DLS2 open. Therefore, if the hoist is operatingwithin this limit with the lobe 38 of the down-limit switch actuatingcam 36 holding the contacts DLS2 open, energization of the highspeedrelay coil HR is prevented. This prevents energization of coil HR andallows the normally closed contacts HSI to remain in closed circuitposition so that the relay coil LR of the low-speed relay may beenergized and control the operation of the motor I2. Unless coil HR isenergized contacts HS3 and HS4 remain open. When, however, the selectorswitch SS is in an up position, as shown, closing the contacts SSU, thecondition of the contacts DLS2 is immaterial and will not affect theoperation of the hoist at either low speed or high speed in an upwarddirection.

Manual operation of the DB button of the manual switch MS acts to closecontacts DN2,

and continued downward movement of the DB button acts to open thecontacts DNI to control the operation of the motor I2 and cable drum I4in much the same manner as the up button UB, but in the oppositedirection. In this case closure of the contacts DN2 energizes the downdirection control circuit G from the line LI to the closed contactsDLSI, the relay coil DNR of the down direction relay through the nowclosed contacts DN2 to the line L2. Energization of the relay coil DNRwill close the contacts DNSZ of the relay coil DNR, closing the circuit2 through the low-speed relay coil LR from the line LI through thenow-closed contacts ASI, the relay coil LR, contacts DNS2, and throughthe nowclosed contacts DN2 to the line L2. Energization of the relaycoil LR causes the contacts LSI to be closed, and energization of therelay coil DNR causes the contacts DNS3 and DNS4 to be closed forcontrolling the circuit for the motor I2, so that the motor I2 and thecable I4 are operated in a direction for lowering of the hoist at a slowspeed.

If now the down button DB is pressed inwardly still further so that thepin 3I engages the bridging bar 28 and forces it downwardly to open thecontacts DNI, the accelerating control circuit I will be de-energized,and, as heretofore stated, after the timing condenser AC has dischargedthrough the relay coil AR, the contacts ASI will be opened and thecontacts AS2 will be closed. Closure of the contacts AS2 closes thecircuit 4 through the high-speed relay coil HR from the line LI throughthe now-closed contacts AS2, the relay coil HR, the now-closed contactsDLS2, USI, DNS2, and DN2 to the line L2. If the down button DB ismaintained in this position, as the hoist reaches its low position theworin 33 driven through gearing 35 by the cable drum I4 will rotate thedown limit switch actuating cam 35 so that its lobe 38 engages theoperating rod 39 of the down-limit switch DLS to open the contacts DLS2which de-energizes the circuit 4 through the high-speed relay coil HR,causing the lowspeed operating circuit 2 of the motor I2 to be energizedin a manner similarly to that set forth hereinbefore. Continued rotationof the cable drum I4 in a direction to lower the hoist causes cam lobe38 to take up the lost motion between pin 4I and bar 40 to open the downdirection control circuit 6 to open contacts DNSZ which deenergizes thelow-speed control circuit 2. Deenergization of the circuits 2 and 6opens contacts LSI, DNS3, and DNS4 to stop the motor I2 and drum I4.

Immediate release of the down button DB prior to the hoist reaching thedown end of its travel and prior to being operated by the down-limitswitch acts to place the motor I2 at its low-speed operating conditionuntil discharge of the timing condenser DRC through the relay coil DR,at which time the contacts DSI' are opened to deenergize the lowspeedrelay coil LR, causing the motor I2 to be Cle-energized and stop.Release of the down button DB sufficient to close contacts DNI andmaintain contacts DN2 closed, de-energizes the high-speed controlcircuit 4 due to the energization of circuit I and coil AR and energizesthe low-speed control circuit 2 to open contacts HS3 and HS4 and toclose contacts LSI for placing the circuit 8 of motor I2 in condition tooperate the motor in the down direction at low speed. Subsequent releaseof the button DB opens contacts DN2 to de-energize circuits 2 and 6lcausing contacts LSI, DNS3, and DNS! to open to stop the motor I2.

As described above, the timing condenser AC and control relay AR becomeenergized immediately upon closure of the line switches LSI and LS2, inreadiness f or starting operation in either the raising or loweringdirection. Under some conditions, it may be desirable to delay theinitial energization of condenser AC and relay AR until the startingbutton UB or DB, as the case may be, is actuated to either a high speedor a low speed running position.y Such operation may be effected bymoving the indicated transfer switch T from its full line position, to aposition in which it is disconnected, from terminal 5I, and is connectedto terminal 52. Terminal 52 is connected to a conductor 53 which in turnis connected to line L2through the previously described control relaycontact DSI. Under the conditions now being described, when button UB,for example, is moved from the off position to the low speed position,such action connects circuit I to line I, through contacts UPI,conductor I9 and contacts UP2, which action immediately energizes relayAAR and condenser AC. `Even if button UB is quickly moved from the offposition to the full speed position, there is a short interval, as abovedescribed, during which both contacts UPI and UP2 become energized,which interval is long enough to fully charge condenser AC and causerelayAR, to assume the energized position. Similar comments apply to anoperation of button DB to either the low speed or the high speedposition.

Similarly, when the button UB or DB is moved from the running positionto the off position, there is a short interval during which both of thecorresponding contacts UPI' and UP2, or DNI and DN2, are closed, duringwhich interval condenser AC and relay AR are, respectively, rechargedand re-energized. To positively insure such a recharging andre-energizing` the connection through conductor 53 and contacts DSI,afford a positive re-energizing and recharging circuit for rela-r AR.and condenser AC, under decelerating conditions.

This invention provides a simple control arrangement whereby a hoist,irrespective of the operator, must always be started at low speed andcannot be immediately brought to high speed in amanner which mightdamage the work being transported or cause the hoist cable t'o be brokenbut must rst be operated for a predetermined time interval through itslow speed connections,

thereby providing a desirably gradual rate of ac- The control providesceleration of the hoist. means for selectively renderingthe hoistoperable at only low speeds adjacent the low end of its range of travel.The circuit also provides means whereby the hoist, whether `movingupwardly or downwardly at the time, is not stoppedimmediately from the.high speed operation `but 4must go through a predetermined time periodof operation through its low speed connections before it will stop, thusproviding a desirably gradual rate of deceleration and preventing damageto the materials being carried by the hoist.

What is claimed and is desired to be secured by United States LettersPatent is as follows:

l. In a multi-speed electric control system, a first circuit operable tocontrol operation of a mechanism at a rst speed, a second circuitoperable to control operation of said mechanism at a second speed, a rstcircuit controlling means having two operating positions, said means inone Afl() of said positions being operable to energize said irst circuitand in the other of said positions being operable to energize saidsecond circuit, a third circuit for controlling said controlling means,a second circuit controlling means having three positions of operation,said second controlling means being operable in one of said positions toenergize said third circuit and in the second of said positions toenergize said second circuit and in the third of said positions todeenergize said third circuit. l 2. In a multi-speed electric controlsystem, a iirst electric circuit operable to control operation of amechanism at a first speed, a second electric circuit operable tocontrol operation of a mechanism at a second speed, a first acceleratingrelay controlling means having two positions of operation, said meanswhen in one of said positions being operable to energize said rstcircuit and when in the second of said positions being operable toenergize said second circuit, a third electric circuit operable tocontrol said first controlling means, said first controlling means beingoperable upon energization of said third circuit to move to said oneposition and upon de-energization to move to said second position, asecond up controlling means having three positions of operation, saidsecond means being operable in the first of said positions to energizesaid third circuit `and in the second of said positions to energize saidiirst circuit and maintain said third circuit energized and in the thirdof said positions to energize said second circuit and to de-energizesaid third circuit, and time delay means operable upon de-energizationof said third circuit to maintain said iirst controlling means in saidone position for a predetermined time interval.

, 3. In a multi-speed electric control system, a first circuit operableto control the operation of a mechanism at a rst speed, a second circuitoperable to control the operation of the mechanism at a second speed, afirst controlling means yhaving two operation positions, said meansbeing operable in one of said positions to render said first circuit incondition to control said mechanism and in the second of said positionsto render said second circuit in condition to control said mechanism, athird electric circuit operable to control said means, a secondcontrolling means having three positions, said second controlling meanswhen in the first of said positions being operable to control said thirdcircuit whereby said first controlling means is placed in its said oneposition, said second controlling means when in the second of saidpositions being operable to control said iirst circuit for operation ofsaid mechanism, said second controlling means when in the third ofsaidpositions being operable to control said third circuit whereby saidiirst controlling means is placed in its said second posi- ',tion, andmeans for delaying the operation of said rst controlling means forchanging from said one to said second controlling positions untii apredetermined time interval has elapsed after said second controllingmeans has been placed in said third position from said second position.4. In a multi-speed electric control cirucit for an electricallyoperated motor, a iirst electric circuit for energizing the motor tooperate at a first speed, a second electric circuit for energizing themotor to operate at a second speed, an energizable circuit controllingvmeans operable upon energization to energize said iirst circuit andoperable upon de-energization to energize said second circuit, a thirdelectric circuit for energizing said circuit controlling means, meansoperable upon de-energization of said third circuit for maintaining saidcircuit controlling means energized for a predetermined time interval,and means operable to energize said first circuit and to de-energizesaid third circuit.

5. In a multi-speed electric control circuit for an electricallyoperated motor, a ilrst circuit operable to energize the motor foroperation at a first speed, a second circuit operable to energize themotor for operation at a second speed, switch means for energizing saidiirst circuit, an energizable accelerating control means, a thirdcircuit for energizing said accelerating means, and time delay means forenergizing said accelerating means and operable upon de-energization ofsaid third circuit to maintain said accelerating means energized for apredetermined time interval, said accelerating control means beingoperable upon de-energization to energize said second circuit,

6. In a multi-speed electric control circuit for an electricallyoperated motor, a first circuit operable to energize the motor foroperation at a first speed, a second circuit operable to energize themotor for operation at a second speed, switch means operable by saidmotor for de-energizing each of said circuits in predeterminedsuccessionl a second switch means for energizing said first circuit, anenergizable accelerating control means, a third circuit for energizingsaid accelerating means, and time delay means for energizing saidaccelerating means and operable upon de-energization of said thirdcircuit to maintain said accelerating means energized for apredetermined time interval, said accelerating control means beingoperable upon de-energization to energize said second circuit.

7. In a multi-speed electric control for a hoist, means operating thehoist in one of two directions and operable at a rst speed and at asecond speed, a, rst control circuit operable to cause said hoist totravel at said first speed, a second control circuit operable to causesaid hoist to travel at said second speed, means for actuating saidcircuits in sequence so that the hoist will start its movement at saidfirst speed and continue its movement at said second speed, time controlmeans operable to determine the time interval between the time ofactuation of said second circuit by said actuating means and the timesaid second circuit becomes effective to cause the hoist to operate atsaid second speed, and control means operable to render said secondcircuit ineiiective during movement of said hoist within a predeterminedrange of movement in one direction.

8. In a multi-speed electric control for a. hoist, means operating thehoist in one of two directions and operable at a first speed and at asecond speed, a rst control circuit operable to cause said hoist totravel at said first speed, a. second control circuit operable to causesaid hoist to travel at said second speed, means for actuating saidcircuits in sequence so that the hoist will start its movement at saidrst speed and continue its movement at said second speed, time controlmeans operable to determine the time interval between the time ofactuation of said second circuit by said actuating means and the timesaid second circuit becomes effective to cause the hoist to operate atsaid second speed, means op- -erable subsequent to the operation of saidtime control means to render said first circuit ineffective, and controlmeans operable to render said second circuit ineffective during movementof said hoist within a predetermined range of movement in one direction.

9. In a multi-speed electric control system, a first circuit operable tocontrol the operation of a mechanism at a rst speed, a second circuitoperable to control the operation of the mechanism at a second speed,circuit controlling means operable to control said circuits inpredetermined succession, and means including electric energy storagemeans operable to determine the time interval between control of one ofsaid circuits and the control of the other of said circuits.

10. In a multi-speed electric control system, a first electric circuitoperable to control operation of a mechanism at a first speed, a secondelectric circuit operable to control operation of a mechanism at asecond speed, a first accelerating relay controlling means having twopositions of operation, said means when in one of said positions beingoperable to energize said first circuit and when in the second of saidpositions being operable to energize said second circuit, a thirdelectric circuit operable to control said first controlling means, saidfirst controlling means being operable upon energization of said thirdcircuit to move to said one position and upon dcenergization to move tosaid second position, a second up controlling means having threepositions of operation, said second means being operable in the rst ofsaid positions to energize said third circuit and in the second of saidpositions to energize said first circuit and maintain said third circuitenergized and in the third of said positions to energize said secondcircuit and to deenergize said third circuit, and time delay meansincluding electric-energy storage means operable upon de-energization ofsaid third circuit to maintain said first controlling means in said oneposition for a predetermined time interval.

WILLIAM G. WAMSLEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,233,169 Jones Feb. 25, 194i2,273,988 Pinto Feb. 24, 1942

